Please provide specific details about your assignment and what you're confused about. There's not enough information in your question for me to understand what you need help with.
until now i just have geodatabase
they tell me to do a project of modeling network
in my data I have roads and cities
so I don't have any idea about modeling what to do?
they just say i should use python code
this is why am here am trying to understand network modeling
I think you should start with our tutorials so you can understand the types of modeling and analysis that the Network Analyst extension can do. We have tutorials to explain the different types of analysis and tutorials to help you create a network dataset using your street data. These tutorials don't use python, but you should still start here so you can understand conceptually what you're doing.
Once you know what you want to do, you can read about how to do network analysis with python.